Technical Field
Exemplary embodiment(s) of the present disclosure relate to industrial lead-acid battery data monitoring apparatus and, more particularly, to a low-cost clamp-on sensor that monitors current, voltage, and battery temperature.
Background of the Invention
A Battery Data Module, hereinafter “BDM”, is a system for measuring analog signal parameters continuously from a battery, taking setup configuration information, and storing battery event and data records (e.g., battery current, battery voltage, mid cell battery voltage, battery temperature, electrolyte level, etc.). The BDM will calculate various battery usage parameters and store said values in nonvolatile memory (e.g., read-only memory, flash memory, ferroelectric RAM, magnetic computer storage, etc.) upon the collection of such values.
BDM data can be divided into the following categories: 1) Configuration Data; 2) Summary Data; and 3) Event Data. Configuration Data includes data necessary to manage the operation of the BDM (i.e., battery serial numbers, truck serial numbers, battery configuration, service date, alarm thresholds, conditions). Summary Data is comprised of a plurality of data collected over the operating life of the BDM and optionally over user configurable time intervals. Event Data is a record of operation of the battery to which the BDM is attached. Events are recorded for each operating state of the battery (i.e., battery charge, discharge, idle), BDM start and stop, and event thresholds. Furthermore, event data is used to compile an accurate record of battery use.
The BDM is responsible for collecting data and using the configuration parameters to form these records and store them in nonvolatile memory.
Typical industry software configuration is done locally (i.e., by a direct wired linked connection, by a wireless linked connection) allowing a service technician to configure customer parameters which ultimately provide the configuration and setup of the BDM customized to the battery application. This process is dated and highlights a major weakness in existing BDMs, the necessity to be on-site to configure BDMs for a particular application. The service tech must physically be present in order to properly configure the BDM, so that they can properly enter the pertinent information. When human errors occur in the configuration process, the previously collected data under the erroneous configuration is corrupt and lost. The new configuration must be corrected on the BDM and the newly collected data with the corrected configuration can be tracked moving forward. In essence, configuration needs to be programmed into the BDM before it can properly calculate and form meaningful summary and event data records for the battery on which it resides. Moreover, configuration must be performed locally on-site with proper tools and trained service technicians.
Typical summary and event records are stored locally on the BDM in nonvolatile memory. As mentioned previously, there is a strong relationship between configuration and event and summary records. Embedded in the configuration are various parameters that allow calculating and forming summary and event records. Summary and event data records can then be calculated and formed from these typical parameters. Summary data is a collection of values recorded while the BDM is in operation. Three collections of data are as follows: 1) Total; 2) Interval 1; 3) Interval 2. Total data is a summary of all data recorded since BDM installation. The total data may only be reset by a hard reset of the BDM. Interval 1 and Interval 2 are two sets of data which can be reset by user control. These summary collections can be used to accumulate data over specific time periods of for certain operating conditions.
The BDM event log is a record of all battery activity. A record is entered into the log on each change of operating state (e.g., idle, charging, and discharging). In addition, an event record is generated when the BDM operation is started or stopped. A BDM start event would occur on power-up when the BDM is properly configured and when the BDM is commanded to start via the communications protocol. A stop event occurs when the BDM is commanded to stop via the communications protocol. Loss of power to the BDM will not generate a stop event, however. The BDM can record alarm, status and error events according to the configuration of the device. A plurality of event records is stored in the log in chronological order. When the log is full, the oldest record is overwritten.
The BDM must be a configured intelligent machine in order to calculate and formulate accurate records. Calculated values such as Amper Hours (AHRs), State of Charge (SOC), and time stamped data must be accurate and maintained locally. If the date is not configured properly, the data collected becomes corrupted, and as a result, the BDM's time setting must be corrected to ensure that future data has the proper time stamp. The corrupted data is no longer usable nor salvageable. Likewise, any SOC calculations must possess an accurate battery capacity configuration. Furthermore, any new calculations proposed (i.e., lifetime predictors) must be custom programmed on end devices and added to the protocol.
Exception reporting is primarily the preferred method for existing systems as it only notifies users when there is a warranty-threatening or application issue. Most customers do not want to review records to determine whether there is an issue worth noting. Typically exception reporting will be automated and push alerts via email or text messages. If any records are changed or added, the BDM will require reprogramming. Unfortunately, all devices deployed need to be upgraded individually, which creates service issues and possible loss of data in the module. This does provide a reduction in the amount of data stored, but requires the BDM to perform calculation and event detection methods. Coincidently, this increases the complexity of the embedded controller on the BDM, leading to more potential firmware bugs.
Typical industry hardware is comprised of BDMs that utilize external current sensors and wiring attachments to electrically power the unit from the battery. Typically, the BDM is powered by attaching wires to the positive and negative terminals of the battery or cables attaching to these terminals. These connections are usually light gauge wires and care must be taken when handling batteries, as they can be caught and torn on heavier components of the battery and/or a vehicle (e.g. forklift or pallet truck for material handling) in which the battery is installed when removal and installation on the vehicle occur. Depending on the connection method of these wires, dissimilar metal and acid corrosion can occur on the connectors used. The two methods employed for current sensing are Hall Effects and current shunts.
Hall Effect sensors incorporate a ferrite C-core and need to be electrically powered and sensed via a wiring harness from the BDM. In addition, battery power cables need to be removed from connectors to insert into the C-core of the Hall Effect and then reattached to the connector. Current shunts come in two different varieties: 1) Purchased Calibrated Shunts and 2) Field Calibrated Battery Straps. Purchase calibrated shunts require cutting power cables, applying lugs and attaching to the shunt. Furthermore, wires need to be run back to the BDM for sensing and the shunt needs to be packaged to electrically isolate. Field calibrated shunts eliminate these issues by utilizing existing battery straps that interconnect battery cells and by performing a field calibration procedure to calibrate. Calibration must be done on each install and requires a trained technician, test instruments and setup. The strap cannot be arbitrarily closed and wired to the BDM due to voltage potentials of the BDM sensing circuits. Additionally, the battery may be manufactured with a purchased calibrated shunt, but the shunt must be sized to the BDM used, and therefore becomes custom build with a nonstandard battery strap.
There are other reliability issues related to this special/custom production sequence including shunt dissimilar material, acid corrosion, and heating issues. Consequently, this has not been standardized and due to issues related to this implementation probably will not materialize in the future. Because of these issues and the need for field installs, trained technicians are required to properly install these BDMs. This does not promote nor enable high volume installations and scalability. The cost of ownership is not just the BDM purchase price, but also the cost of installation and resolution of associated human errors that require on-site rectification.
Needs exist for improved systems for monitoring and reporting batter usage.